calculating every possible combinations of a given array

combinations.ts

// credit: https://codesandbox.io/s/all-combinations-of-words-v14d9

function combinations(words: string[]): string[][] {
  const combs: string[][] = [[]];
  for (const word of words) {
    combs.push(
      ...combs.map((comb) => {
        return [...comb, word];
      })
    );
  }
  return combs;
}

console.log(combinations(["1"]));
console.log(combinations(["1", "2"]));
console.log(combinations(["1", "2", "3"]));

function combinationsRecursive(words: string[]): string[][] {
  if (words.length === 0) {
    return [[]];
  }
  const base = combinationsRecursive(words.slice(0, -1));
  const wordToAdd = words[words.length - 1];

  const allCombinations = [...base];

  for (const baseCombination of base) {
    allCombinations.push([...baseCombination, wordToAdd]);
  }

  return allCombinations;
}

console.log(combinationsRecursive(["1"]));
console.log(combinationsRecursive(["1", "2"]));
console.log(combinationsRecursive(["1", "2", "3"]));